Hand held power tools, such as circular saws, grinders and the like, in which the blade or other cutting tool is protected by a spring biased, movable guard are well known in the art. Typically, the guard is designed to be moved to an open position by contact with a workpiece as the cutting blade is moved through the workpiece. In cutting very soft material, such as soft wood, the spring biased blade guard can scratch or otherwise mar the surface of the workpiece. In addition, it has long been a problem that in using such hand held power tools to cut a thin slice from a workpiece or to make a shallow angle cut, the guard typically does not engage the workpiece squarely or completely. This may cause the power tool to shift laterally during the cut, thereby rendering the cut imprecise and perhaps ruining the workpiece. Thin slices cut from a workpiece also may become jammed between the blade and the guard before the guard has moved sufficiently toward the open position.
In an attempt to overcome at least some of these problems, power tool operators frequently will use one hand to hold the movable guard in its open position. This leaves only one hand to hold and guide the power tool and no hand is left free to hold the workpiece.
Thus, employing one hand to hold the guard open reduces operator control of the cutting operation and reduces work quality and safety. Power tool operators also have been known to disable the guard, such as by jamming it permanently in its full open position, or even to remove the guard entirely. Disabling or removing the blade guard obviously presents a significant safety risk to the tool operator.
Attempts have been made to provide means for retaining a movable guard member in a retracted et al a circular saw is disclosed wherein a slidable pin is mounted on a movable saw blade guard member. To lock the movable guard member in its open position finger pressure is applied to the outer head of the slidable pin. The inner end of the pin registers with an opening in an upper, fixed portion of the guard. It is a disadvantage of this design that the operator does not fully control the release of the lower guard member. As noted in the patent, slight pressure against the end of the movable guard causes the slidable pin to be released from the opening in the fixed guard, allowing the movable guard to return to the closed position. It is another disadvantage that the operator must either cause pressure against the end of the movable guard or must manually manipulate the spring and lower guard member to release the movable guard to cause it to return to the closed, protecting position.
Another mechanism for retracting a movable lower guard of a portable saw is seen in U.S. Pat. No. 3,787,973 to Beisch et al. The manually operable retractor mechanism of Beisch et al is connected by direct linkage to the movable lower guard member. The mechanism locks the lower guard in the retracted position. Release of the lower guard member is not fully controlled by the tool operator, however, since, as in the Laube et al patent discussed above, pressure against the movable member (moving it further toward its open position) will automatically release it and allow it to return to its closed position.
It is an object of the present invention to provide a retainer mechanism for a movable tool guard. In particular, it is an object of the present invention to provide a retainer mechanism which in at least certain preferred embodiments overcomes some of the disadvantages inherent in devices previously known to the art. Additional objects and features of the invention will be better understood from the following disclosure.